Gas supply system for gas blast circuit breaker

ABSTRACT

An air blast circuit breaker requires two constantly available supplies of compressed air, one at low pressure (370 psi) and the other at high pressure (1,500 psi). An air compressor takes air at atmospheric pressure, compresses it to 500 psi, and supplies it through an air drier to a first stage reservoir or receiver. Air is supplied on demand from the first stage reservoir to replenish a second stage reservoir or receiver which supplies the low pressure air to the breaker. Air is also supplied on demand from the first stage reservoir to operate and to feed a booster pump which compresses the feed-air from 500 psi to 1,500 psi and replenishes a third stage reservoir or receiver which supplies the high pressure air to the breaker. Exhaust operating air from the booster pump is supplied to the second stage reservoir. After use in the breaker, the air is exhausted to atmosphere.

United States Patent Clark [451 May 9, 1972 [54] GAS SUPPLY SYSTEM FOR GAS BLAST Attorney-Thomas F. Kirby, Lee H. Kaiser and Robert B. Ben- CIRCUIT BREAKER Son [72] Inventor: Thomas F. Clark, Dorchester, Mass. 57] ABSTRACT [73] Asslgnee: Al us'Chalmers Manufmnmlg Company An air blast circuit breaker requires two constantly available Milwaukee, Wis. supplies of compressed air, one at low pressure (370 psi) and [22] Filed; 10 1970 the other at high pressure (1,500 psi) An air compressor takes air at atmospheric pressure, compresses it to 500 psi, PP N04 96,734 and supplies it through an air drier to a first stage reservoir or receiver. Air is supplied on demand from the first stage reser- [52] US. Cl. ..200/l48R voir to replenish a Second stage reservoir or receiver which [51] Int. Cl ..H0lh 33/54 supplias the low pressure air to the breaker Air is also [58] Field of Search "200 48 R 148 B 148 E 148 G plied on demand from the first stage reservoir to operate and to feed a booster pump which compresses the feed-air from [56] References Cited 500 psi to 1,500 psi and replenishes a third stage reservoir or receiver which supplies the high pressure air to the breaker. UNITED STATES PATENTS Exhaust operating air from the booster pump is supplied to the second stage reservoir. After use in the breaker, the air is ex- 3,47l,666 10/1969 Barkan ..200/148 B hausted to atmosphere Primary Examiner-Robert S. Macon 10 Claims, 1 Drawing Figure GAS SUPPLY SYSTEM FOR GAS BLAST CIRCUIT BREAKER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to compressed gas or air supply systems, and particularly, to those used with gas or air operated apparatus such as gas or air blast type electric circuit interrupters.

' 2. Description of the Prior Art As used hereinafter the word air is used to connote any type of suitable gas, unless indicated otherwise.

Some prior art apparatus, such as air blast type electric circuit breakers, required two constantly available supplies of compressed air, one supply at a low pressure, such as about 370 psi, and the other supply at an extremely high pressure, such as about 3,000 psi. The'supply of low pressure air was used for insulation purposes within the circuit breaker and also to actuate controls which effected opening and closing of the circuit breaker contacts. The supply of high pressure air was used to effect the actual separation of the circuitbreaker contacts and to extinguish electric arcs coincident with contact separation. In practice a conventional expensive high pressure compressor raised ambient air from atmospheric pressure to about 3,000 psi and supplied it to a high pressure reservoir which served as the high pressure supply and also, by means of appropriate pressure reducing valves, as the low pressure supply. This approach, while satisfactory for its intended purpose, had several disadvantages. First it required high pressure storage of large quantities of air and used a wasteful expansion cycle to obtain necessarily dry air. This implies extensive use of expensive high pressure piping, valves and fittings which are difficult to assemble and raises component and assembly costs. Second, conventional high pressure compressors tend to contaminate the compressed air with lubricant vapor which creates an explosion hazard, causes deterioration of some components and inhibits reliable performance of valves and other moving parts. Third, reliance on the high pressure supply as the low pressure supply is wasteful of energy and causes needless wear on the compressor because more air than is actually required for high pressure use is raised to high pressure levels. It is desirable, therefore, to provide new and improved compressed air supply systems which overcome the aforesaid disadvantages and have other advantages.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided apparatus, such as an air blast circuit breaker, which requires two constantly available supplies of compressed air, one supply at low pressure (on the order of 370 psi) and the other at high pressure (on the order of 1,500 psi). A lowpressure type air compressor means takes air at atmospheric pressure, compresses it to a pressure level (about 500 psi) which is greater than the aforesaid low pressure level but less than the high pressure level, and supplies it through an air drier means,

such as a heaterless, regenerative air drier to a first stage reservoir or receiver means. Air is supplied on demand from the first stage receiver through pressure regulating or reducing valve means to replenish a second stage reservoir or receiver means which supplies the low pressure air to the circuit breaker. Air is also supplied on demand from the first stage reservoir to operate (through another pressure regulating or reducing valve means) and to feed oilless high pressure booster pump means which compresses the feed-air to the high pressure level and replenishes a third stage reservoir or receiver means which supplies the high pressure air to the circuit breaker. Exhaust operating air from the booster pump is conserved and supplied to the second stage receiver. After use in the circuit breaker, the low pressure and high pressure air is exhausted to atmosphere.

OBJECTS It is an object of the present invention to provide new and improved compressed air supply systems for use in apparatus, such as air blast electric circuit breakers, which require constantly available supplies of air at different pressure levels.

Another object is to provide such systems which eliminate the need to initially compress unnecessarily large quantities of air to extremely high levels; which eliminate costly and complex components required in extremely high pressure systems; which eliminates explosion hazards and contamination problems associated with systems employing conventional high pressure type air compressors; and which are more efiicient, less costly to operate, conserve energy and reduce wear on system components.

Another object is to provide such systems which are safer, less costly and more reliable than functionally equivalent conventional systems and which employ standard commercially available components.

Another object is to provide such systems which employ more efficient air drying means and eliminate the need for expansion cycles, strainers and water sumps.

Other objects and advantages of the invention will hereinafter appear.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing illustrates a preferred embodiment of the invention but it is to be understood that the embodiment illustrated is susceptible of modifications with respect to details thereof without departing from the scope of the appended claims.

In the drawing:

The single FIGURE isa schematic or diagrammatic showing of a compressed air supply system used with an air blast type electric circuit breaker in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, the numeral 10 designates apparatus, such as an air blast circuit breaker, which requires a first supply of compressed air at one low pressure level (about 370 psi, for example) and a second supply of compressed air at another higher pressure level (about 1,500 psi, for example). It is to be understood, for example, that circuit breaker 10 is adapted for controlling a high voltage, high current electrical transmission line and that it requires the low pressure air for electrical insulation and control purposes and the high pressure air for contact operation and are extinction purposes. Furthermore, circuit breaker 10 may comprise one or more polesto control one or more phase lines, respectively.

The system for supplying low pressure and high pressure compressed air to circuit breaker 10 comprises air compressor means, such as a conventional low pressure compressor 12, driven by an electric motor 14 whichreceives ambient air at atmospheric pressure through an inlet 16, compresses it to a pressure level of about 500 psi or above, and discharges it through an outlet 18. Compressor l2 raises the air to a pressurelevel which is greater than the low pressure level of 370 psi but substantially less than'the high pressure level of 1,500 psi required by circuit breaker 10.

Outlet 18 of compressor 12 is connected by an air line 20 to an inlet 22 of an air drier means 24 having an outlet 26. Drier 24 is understood to be of the heaterless regenerative type and contains a suitable dessicant 28. Drier 24 removes virtually all moisture from the compressed air leaving compressor 12.

Outlet 26 of air drier 24 is connected by an air line 30, which contains a check valve means 32, to an'inlet 34 of a first stage reservoir or receiver means 36 which stores the compressed air at a pressure level of about 500 psi and makes it available on demand, as hereinafter described. It is to be understood that receiver 36 is provided .with such pressure switches (not shown) as are necessary to effect operation of compressor motor 14 and compressor 12 to maintain the desired pressure range in receiver 36. Check valve 32 prevents back-flow of compressed air from receiver 36.

Receiver 36 is provided with a first outlet 38 which is connected by an air line 40, which contains a regulating valve 42, to a first inlet 44 of a second stage reservoir or receiver means 46 which stores compressed air at the aforesaid one low pressure level of about 370 psi for use on demand by circuit breaker 10 which requires a continuous supply of low pressure air. Regulating valve 42 effects a pressure reduction in the compressed air flowing from receiver 36 to receiver 46.

Receiver 36 is also provided with a second outlet 48 and a third outlet 50 which connect to a high pressure booster pump means 52, as hereinafter described. Booster pump means 52, shown schematically, is understood, for example, to comprise a commercially available reciprocating type oil-free air-driven unit having a housing 54 in which a piston 56 is disposed. Piston 56 employs piston rings 58 made of low-friction materia], such as Teflon, and thus requires no oil in the air chambers. Housing 54 contains an operating air chamber 60 having an inlet 62 and an outlet 64. Housing 54 also contains a feedair chamber 68 having an inlet 70 and an outlet 72.

Operating air for booster pump 52 is supplied from second outlet 48 of first receiver 36, through an air line 74 (which contains regulating valve means 76), to inlet 62 of operating air chamber 60 of the booster pump and drives piston 56 in high speed reciprocating fashion. The operating air from chamber 60 of booster pump 52 is exhausted after use and at reduced pressure from outlet 64, through an air line 78 (which contains a check valve 80) to a second inlet 82 in second stage receiver 46 and thus is not wasted. Check valve 80 prevents back-flow of compressed air from receiver 46.

Feed air for booster pump 52 is supplied from third outlet 50 of first receiver 36, through an air line 84 to inlet 70 of feed-air chamber 68 of the booster pump and is compressed by piston 56 from a pressure level of 500 psi to a higher pressure level of 1,500 psi or above from whence it is supplied through an air line 88 (which contains check valve means 90) to an inlet 92 in a third stage reservoir of receiver means 94. Receiver 94 stores compressed air at the aforesaid second higher pressure level of 1,500 psi for intermittent use on demand by circuit breaker 10.

Second stage receiver 46 and third stage receiver 94 are provided with outlets 96 and 98, respectively, which are connected by air lines 100 and 102, respectively, to circuit breaker 10. Line 100 contains a check valve 104 which prevents back-flow of compressed air from breaker 10 which, it is to be understood, requires a continuous supply with low pressure air for insulation and control purposes. Line 102 contains a regulating valve or blast valve 106 which allows high pressure air flow or blast into circuit breaker 10 during actual opening and closing operations. At or near the end of an operation of circuit breaker 10, an exhaust valve 108 which is connected to the breaker by an air line 110 opens to exhaust high pressure air to atmosphere and to return the pressure in the circuit breaker to its normal low pressure level and then valve 108 closes to maintain this latter pressure level.

It is to be understood that the aforedescribed system comprises such pressure sensitive switches, valves and controls as are required to insure the necessary pressure levels in the several receivers. Furthermore, although the word air is used throughout the description it will be apparent that the principles disclosed contemplate the use of gases other than air, if a system should require it. In addition, the specific pressure levels given are for purposes of illustration and other pressure levels could be used in practice provided the relative relationships exist. Pumps such as booster pump 52 are known and available, for example, from Haskel Engineering and Supply Co., Glendale, California. Components and elements in the system may be made redundant, as required, to increase system reliability.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a system for supplying apparatus with a supply of compressed gas at one pressure level and a supply of compressed gas at a higher pressure level than said one pressure level, in combination:

compressor means for compressing gas to a pressure level which is greater than said one level but less than said higher level,

first reservoir means for receiving compressed gas from said compressor and for storing it so as to be available on demand,

booster pump means for receiving compressed gas from said first reservoir for operating purposes and for feed purposes,

second reservoir means for receiving compressed gas from said first reservoir and for receiving exhaust operating gas from said booster pump means and for supplying it on demand at said one pressure level to said apparatus,

and third reservoir means for receiving compressed feed gas from said booster pump means and for supplying it on demand at said higher pressure level to said apparatus.

2. A system according to claim 1 comprising gas drier means between said compressor means and said first reservoir means.

3. A system according to claim 2 wherein said gas drier means is of the heaterless, regenerative type and wherein said booster pump means is of the oilless type.

4. A system according to claim 2 comprising pressure reducing valve means between said first and second reservoir means.

5. A system according to claim 4 comprising check valve means between said compressor means and said first reservoir means;

regulating valve means between said first and second reservoir means;

regulating valve means between said first reservoir means and said booster pump means to regulate the pressure of the operating gas;

check valve means between said booster pump means and said second reservoir means;

check valve means between said booster pump means and said third reservoir means;

check valve means between said second reservoir means and said apparatus;

and control valve means between said third reservoir means and said apparatus.

6. A system according to claim 1 comprising a gas blast circuit breaker as said apparatus.

7. A system according to claim 6 wherein said one pressure level is about 370 psi, wherein said higher pressure level is about 1,500 psi, and wherein said compressor means compresses said gas to about 500 psi.

8. A system according to claim 5 wherein said one pressure level is about 370 psi, wherein said higher pressure level is about 1,500 psi, and wherein said compressor means compresses said gas to about 500 psi.

9. In combination:

an air blast circuit breaker requiring a constantly available and continually used supply of compressed air at one pressure level and a constantly available and intermittantly used supply of compressed air at a pressure level higher than said one pressure level;

compressor means for receiving ambient air at atmospheric pressure and for compressing it to a pressure level which is between said one pressure level and said higher pressure level;

air drier means of the regenerative type for receiving air from said compressor means and for drying it,

first reservoir means for receiving compressed gas from said air drier means and for storing it so as to be available on demand,

check valve means between said compressor means and said first reservoir means,

booster pump means of the oilless type for receiving compressed gas from said first reservoir for operating purposes and for feed purposes,

regulating valve means between said first reservoir means and said booster pump means,

second reservoir means for receiving compressed gas from said first reservoir and for receiving exhaust operating gas from said booster pump means and for supplying it on demand at said one pressure level to said circuit breaker,

regulating valve means between said first and second reservoir means,

check valve means between said booster pump means and said second reservoir means,

third reservoir means for receiving compressed feed gas from said booster pump means and for supplying it on demand at said higher pressure level to said circuit breaker,

check valve means between said booster pump means and said third reservoir means,

check valve means between said second reservoir and said circuit breaker,

and control valve means between said third reservoir means and said circuit breaker.

10. A system according to claim 9 wherein said one pressure level is about 370 psi, wherein said higher pressure level is about 1,500 psi, and wherein said first reservoir means stores air at a pressure of about 500 psi. 

1. In a system for supplying apparatus with a supply of compressed gas at one pressure level and a supply of compressed gas at a higher pressure level than said one pressure level, in combination: compressor means for compressing gas to a pressure level which is greater than said one level but less than said higher level, first reservoir means for receiving compressed gas from said compressor and for storing it so as to be available on demand, booster pump means for receiving compressed gas from said first reservoir for operating purposes and for feed purposes, second reservoir means for receiving compressed gas from said first reservoir and for receiving exhaust operating gas from said booster pump means and for supplying it on demand at said one pressure level to said apparatus, and third reservoir means for receiving compressed feed gas from said booster pump means and for supplying it on demand at said higher pressure level to said apparatus.
 2. A system according to claim 1 comprising gas drier means between said compressor means and said first reservoir means.
 3. A system according to claim 2 wherein said gas drier means is of the heaterless, regenerative type and wherein said booster pump means is of the oilless type.
 4. A system according to claim 2 comprising pressure reducing valve means between said first and second reservoir means.
 5. A system according to claim 4 comprising check valve means between said compressor means and said first reservoir means; regulating valve means between said first and second reservoir means; regulating valve means between said first reservoir means and said booster pump means to regulate the pressure of the operating gas; check valve means between said booster pump means and said second reservoir means; check valve means between said booster pump means and said third reservoir means; check valve means between said second reservoir means and said apparatus; and control valve means between said third reservoir means and said apparatus.
 6. A system according to claim 1 comprising a gas blast circuit breaker as said apparatus.
 7. A system according to claim 6 wherein said one pressure level is about 370 psi, wherein said higher pressure level is about 1, 500 psi, and wherein said compressor means compresses said gas to about 500 psi.
 8. A system according to claim 5 wherein said one pressure level is about 370 psi, wherein said higher pressure level is about 1, 500 psi, and wherEin said compressor means compresses said gas to about 500 psi.
 9. In combination: an air blast circuit breaker requiring a constantly available and continually used supply of compressed air at one pressure level and a constantly available and intermittantly used supply of compressed air at a pressure level higher than said one pressure level; compressor means for receiving ambient air at atmospheric pressure and for compressing it to a pressure level which is between said one pressure level and said higher pressure level; air drier means of the regenerative type for receiving air from said compressor means and for drying it, first reservoir means for receiving compressed gas from said air drier means and for storing it so as to be available on demand, check valve means between said compressor means and said first reservoir means, booster pump means of the oilless type for receiving compressed gas from said first reservoir for operating purposes and for feed purposes, regulating valve means between said first reservoir means and said booster pump means, second reservoir means for receiving compressed gas from said first reservoir and for receiving exhaust operating gas from said booster pump means and for supplying it on demand at said one pressure level to said circuit breaker, regulating valve means between said first and second reservoir means, check valve means between said booster pump means and said second reservoir means, third reservoir means for receiving compressed feed gas from said booster pump means and for supplying it on demand at said higher pressure level to said circuit breaker, check valve means between said booster pump means and said third reservoir means, check valve means between said second reservoir and said circuit breaker, and control valve means between said third reservoir means and said circuit breaker.
 10. A system according to claim 9 wherein said one pressure level is about 370 psi, wherein said higher pressure level is about 1,500 psi, and wherein said first reservoir means stores air at a pressure of about 500 psi. 